Method and means for electrolytic production of light metals



April 22, 1930. E. o. BA STQW I 1,755,380

METHOD AND MEANS FOR ELECTROLYTIC PRODUCTION OF LIGHT METALS Filed Nov.1925 GLOISULES F06 ED ELETROL YTE.

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I XV EN TOR.

\ A TTORNES.

Apr, 22, lld33 see EDWIN 0. BARSTOW, OF MIDLAND, MICHIGAN, ASSIGNOR TOTHE DOW CAI: COMPANY, 018 MIDLAND, MICHIGAN, A CORPORATION OF MICHIGANMETHOD AND MEANS FOR ELECTROLYTIC PRODUCTION OF LIGHT METALS Applicationfiled November In the electrolytic production of metallic magnesium, bypassing an electric current through a suitable fused electrolyte, one ofthe difliculties encountered is the collection of the separate moltenglobules of the metal. These, as they are set free, rise to the surfacedue to their lighter specific gravity, but do not readily coalesce, atleast until a considerable mass of the molten metal has accumulated.

3 The-object of the present invention is to provide an improved methodand apparatus whereby such free molten globules of the "metal may bepositively collected together at a selected point in the electrolyticcell, thus facilitating the removal or discharge of the metal.

, To the accomplishment of the foregoing and related ends, the inventionthen consists of the steps and means hereinafter described andparticularly pointed out in the claims, the annexed drawing andfollowing description illustrating but several of the various ways inwhich'the principle of the invention 2 may be carried-out. 4

. In said annexed drawing Fig; 1 is a more or less diagrammatic planview of one type of electrolytic'cell such as is used in the productionof metallic magne- 80 sium, the construction of such cell being modifiedto adapt the same for the collecting together of the molten metalinaccordance.

with the present invention; and Fig. 2 is a vertical section of suchcell, partly on an axial plane and partly onv a plane in front of suchaxial plane, as indicated by the line 2. 2,Fi .1. q

The principal element in the apparatus,

illustrated in the drawing is a cast-iron or steel vessel (1) thatconstitutes the cell-proper and in which the electrolyte is placed andmaintained in molterr conditipn. This vessel at the same timeconstitutes the cathode and,

for the purpose of initially melting the elec- 7 trolyte, the vessel maybe supported in a suitable furnace chamber (not shown).

' Supported in any suitable way within vessel l is an annular diaphragmorpartition (2) of porcelain, fire clay, or equivalent material thatserves to laterally surround the centrally 9, 1925. Serial No. 67,780.

disposed, depending carbon orgraphite anode (3). Neither. the latter,nor such annular diphragm extends entirely down to the bottom of thevessel. The anode, however, extends downwardly beyond the lower edge ofthe diaphragm. A suitable duct, not shown, may be provided if desiredfor supplying the electrolyte to the cathode compartment of the cell, i.e., that portion lying between the wall of the vessel (1) and the an-'nular diaphragm (2); while-a duct (4) is connected with the upperportion of the space within the diaphragm in order to conduct away anygases arising from the anode compartment defined by such diaphragm.-

In the operation of a cell such as the foregoing, the particles of freemolten magne-. sium; many quite small in size, rise to the surface ofthe electrolyte in the aforesaid cathode compartment, and there float asseparate globules which do not readily coalesce and, at the best, form athin film only of the metal, which is dificult to remove either bydipping or through a spout or'equivalent discharge opening. The present1mprovement consists as previously indicated inthe provision of meansfor collecting these free molten globules of metal and in the preferredform illustrated, such means comprise a boxlike chamber (5), lyingbetween the diaphragm (2) and the wall of vessel The respective endwalls of thischamber are submerged below the bath level, but'the lateralwalls rise-well above such level. Two transverse partitions (6) and (7)in said chamber (5) form a sub compartment 8) that is open both aboveand below The second of these partitions (see Fig. 2), it willbe noted,extends downwardly further than the first and in the portion (9) of thechamber adj acent'to the sub-compartment (8) there is located apropeller (10) carried by an externally driven vertical shaft (11), suchpropeller serving when operated to induce a flow of the electrolytethrough the several compartments of chamber (5) in the directionindicated by the arrows.

Only the upper stratum of the electrolyte lying, between the annular"partition (2% and the surrounding Wall of vessel (1) will e af- 1%fected, and, depending upon the size and rate of rotation of propeller(10) this stratum may be circulated at any desired rate of speed so asto be entirely caused to pass through chamber (5) within a stated time.Due to the arrangement of the transverse partitions (6 and 7) within thechamber, as clearly shown in Fig. 2, the particles or globules of moltenmetal are entrapped in the sub-compartment defined by said partitionsand are there collected together to form a mass of molten metal ofsubstantial thickness. From this sub-compartment the metal ma be removedeither by dipping or a suita ly controlled laterally opening sprue ordischarge spout may be provided to conduct the metal from saidcompartment to a point without the cell.

It will be understood that the propeller (10) may be operated eithercontinuously or intermittently. Thus, it may be found satisfactory toinduce a circulation of the upper described and, similarly, I do notlimit myself" to any precise form of trap chamber for collectingtogether the globules or particles of molten metal as they are thuscarried around by the circulating electrolyte.

Oher modesofapplying the principle of my invention may be employedinstead of the one explained, change being made as regards the means andthe steps herein disclosed, provided those stated by any of thefollowing claims or their equivalent be employed.

ll therefore particularly point out and distinctly claim as myinvention 1. 'lhe method of aggregating light metal floating on a fusedelectrolyte, which comprises mechanically circulating sa id electro iytethrough a trapped zone in which the oating metal is arrested.

2. in a method of electrolyzin a fused electrolyte for the production 0'a metal which will float thereon, the step which comprises mechanicallycirculating the surface portion of said electrolyte through a trapadapted to arrest metal floating thereon.

3. A method of electrolyzing a fused electrolyte containing magnesiumchloride for the production of magnesium. metal, which comprises.mechanically circulating the surface layer of said electrolyte througha trap adapted to arrest and retain such floating;

metal.

4. A method of producing a light metal which comprises electrolyzing asuitable fused electrolyte, mechanically driving the upper stratum ofsuch electrolyte about in an approximately circular surface path, andentrapping at one point the free molten globules of metal therein.

5. In a method of electrolyzing a fused electrolyte for the productionof a metal which will float thereon, the step which comprises liberatingsaid metal as such,permitting it to rise to the surface of theelectrolyte, and collecting such metal by mechanically circulating theelectrolyte upon which it floats through a trapped zone.

6. In an electrolytic apparatus for liberating a light metal upon anon-fluid cathode from a fused electrolyte heavier than the metalliberated, the combination with a vessel adapted to contain the fusedelectrolyte, of means to mechanically circulate said electrolyte througha trap within said vessel to arrest metal floating on said electrolyte.

7. In an electrolytic apparatus for liberating a light metal upon anon-fluid cathode from a fused electrolyte heavier than the metalliberated, the combination with a vessel adapted to contain the fuesdelectrolyte and act as cathode, of an anode depending in saidelectrolyte, means to separate products liberated upon the anode fromthose lib erated upon the cathode, and mechanical means to circulate thecatholyte througha trap to skim and arrest metal floating upon thesurface.

8. In an electrolytic apparatus for pro ducing a metal lighter than theelectrolyte,

the combination of a vessel adapted-to contain a fused electrolyte,means for passing an electric current therethrough, means for positivelydriving in a surface circuit the portion of such electrolyte containingfree molten globules of metal, and a trap located in such circuit tocollect the globules together.

9. In an electrolytic apparatus for producing a metal lighter than theelectrolyte, the combination of a vessel of general circular formadapted to contain a fused electrol to and constituting one electrode, asecond e ectrode disposed approximately centrally within said vessel,means for driving the upper stratum of such electrolyte around saidsecond electrode, and a trap-chamber within said vessel disposed in theath of such circulating electrolyte and aa ted to collect together thefree, molten glo ules of'metal therein.

10. In an electrolytic apparatus for producing a metal lighter than theelectrolyte, the combination of a vessel of general circular formadapted to contain a fused electrolyte and constituting one electrode, asecond electrode disposed approximately cen- 3 trally' within saidvessel, means adapted to cause a circulation of the upper stratum ofsuch electrolyte around said second electrode, a chamber lying betweenthe wall of said vessel and said second electrode so as to permit msasso3' such circulating electrolyte to flow therethrough and having atransverse partition arranged to tra and so collect together the ree,molten glo ules of metal in the electro- 5 11. In an electrolyticapparatus for pr duoing a metal lighter than the electrolyte, thecombination of a vessel of general circular form adapted to contain afused electrolyte and constituting one electrode, a second electrodedisposed approximately centrally within said vessel, a chamber lyingbetween the Wall of said vessel and said second electrode, the end wallsof said chamber being submerged so as to permit the upper stratum ofsuch electrolyte to flow thereover, transverse partitions in saidchamber forming a sub-compartment open at the top and bottom, and apropeller in said chamber adjacent said sub-compartment.

12. In an electrolytic apparatus for producing a fused metal lighterthan the fused electrolyte employed, the combination with a suitablevessel adapted to contain said fused 5 electrolyte, of a trap disposedwithin said vessel in said electrolyte to arrest and retain floating.metal, and a mechanically driven means in said vessel to circulate theelectrolyte upon which the metal floats through said tra igned by methis 6th day of November, 1925. i

EDWIN O. BARSTOW.

